... Microsoft said it would dissolve its eight product divisions in favor of four new ones arranged around broader themes, a change meant to encourage greater collaboration as competitors like Apple and Google outflank it in the mobile and Internet markets. Steven A. Ballmer, the longtime chief executive, will shuffle the responsibilities of nearly every senior member of his executive bench as a result.

“To execute, we’ve got to move from multiple Microsofts to one Microsoft,” Mr. Ballmer said in an interview.

It remains to be seen whether more cohesive teamwork, if that is what results from all the movement, will offer the spark that has been missing from so many of Microsoft’s products in recent years....